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Marek Czosnyka, Marcella Balestreri, Luzius Steiner, Piotr Smielewski, Peter J. Hutchinson, Basil Matta, and John D. Pickard

Object. The object of this study was to investigate whether a failure of cerebrovascular autoregulation contributes to the relationship between age and outcome in patients following head injury.

Methods. Data obtained from continuous bedside monitoring of intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP = ABP — ICP) in 358 patients with head injuries and intermittent monitoring of transcranial Doppler blood flow velocity (FV) in the middle cerebral artery in 237 patients were analyzed retrospectively. Indices used to describe cerebral autoregulation and pressure reactivity were calculated as correlation coefficients between slow waves of systolic FV and CPP (autoregulation index [ARI]) and between ABP and ICP (pressure reactivity index [PRI]).

Older patients had worse outcomes after brain trauma than younger patients (p = 0.00001), despite the fact that the older patients had higher initial Glasgow Coma Scale scores (p = 0.006). When age was considered as an independent variable, it appeared that ICP decreased with age (p = 0.005), resulting in an increasing mean CPP (p = 0.0005). Blood FV was not dependent on age (p = 0.58). Indices of autoregulation and pressure reactivity demonstrated a deterioration in cerebrovascular control with advancing age (PRI: p = 0.003; ARI: p = 0.007).

Conclusions. An age-related decline in cerebrovascular autoregulation was associated with a relative deterioration in outcome in elderly patients following head trauma.

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Magdalena Hiler, Marek Czosnyka, Peter Hutchinson, Marcella Balestreri, Peter Smielewski, Basil Matta, and John D. Pickard

Object

The authors explored the relationship between computerized tomography (CT) scan findings and intracranial pressure (ICP) measurements obtained in the first 24 hours of monitoring to identify parameters predicting outcome in patients with severe traumatic brain injury (TBI).

Methods

Intracranial pressure, mean arterial blood pressure, cerebral perfusion pressure (CPP), and pressure reactivity index were measured continuously in 126 patients with severe TBI who were admitted to a neuroscience critical care unit. Mean values in the initial 24 hours of monitoring and in the total period of monitoring were compared with types of injury categorized on the basis of the initial CT scan according to the classification of Marshall, et al., and with Glasgow Outcome Scale scores.

The initial CT scan classification correlated significantly but weakly with ICP measured during the first 24 hours of monitoring (p = 0.036) but not with mean ICP over the total time of intensive care. Both midline shift and the ratio of frontal horn diameter to internal diameter correlated with ICP in the first 24 hours (p < 0.007) and with ICP over the total monitoring period (p < 0.03). Outcome score correlated with initial CT scan findings (p = 0.018), ICP over the total monitoring period (p < 0.0023), pressure reactivity over the total monitoring period (p < 0.0002), and pressure reactivity in the first 24 hours (p < 0.0001) but not with ICP in the first 24 hours. Patients with disturbed pressure reactivity in the first 24 hours after injury had a significantly higher mortality rate than patients with intact pressure reactivity (28.6% compared with 9.5%; p < 0.001).

Conclusions

Patients with severe TBI who have early loss of autoregulation have a worse prognosis. Mean ICP values in patients with diffuse TBI cannot be predicted by using the Marshall CT scan classification.